The present invention relates to a machine for making composite filter mouthpieces for cigarettes or analogous rod-shaped smokers' products. More particularly, the invention relates to a machine for the production of so-called recessed composite filter mouthpieces wherein the outermost part of the filter of the mouthpiece is remote from the free end thereof. Still more particularly, the invention relates to improvements in a machine for making a continuous filter rod which can be subdivided into recessed composite filter mouthpieces.
In many heretofore known machines for the making of recessed filter mouthpieces, the filler of the filter rod is assembled of discrete filter plugs or discrete groups of dissimilar filter plugs which are disposed one behind the other and are separated from each other by gaps which, in the finished mouthpieces, constitute recesses at the free ends of such mouthpieces. A drawback of such machines is that the width of gaps between neighboring filter plugs or groups of filter plugs is not uniform so that the depth of recesses at the free ends of mouthpieces varies from item to item. This is undesirable for a number of reasons, primarily because it is annoying to a smoker who is accustomed to smoking cigarettes with recessed filter mouthpieces and detects that his or her tongue contacts the wad or plug of filter material in the mouthpiece of the lighted cigarette.
Commonly owned East German patent No. 21,211 discloses a machine for the making of recessed filter mouthpieces wherein each mouthpiece contains only one type of filter material. Filter plugs are transported by a drum having peripheral phantom plugs and serving to deliver discrete spaced-apart filter plugs onto a running web of wrapping material whereon the plugs are held by spikes of the garniture or by spikes of a rotating drum. Such machines are not suited for the mass production of composite (multiplex) recessed filter mouthpieces.
U.S. Pat. No. 2,953,878 to Schur discloses a filter rod making apparatus wherein assorted filter plugs are introduced into a tube and the thus obtained groups are pushed axially forwardly to form a continuous filler which is draped into a web of cigarette paper and is thereupon severed to yield composite filter mouthpieces without recesses. The patented apparatus cannot be used for the mass production of composite filter mouthpieces or for the mass production of composite recessed filter mouthpieces because, once the speed of moving parts exceeds a certain value, the filter plug at the end of each group is subjected to excessive mechanical stresses during forward movement toward the trailing end of the filler.
U.S. Pat. Nos. 3,131,612 and 3,143,202 to Rowlands disclose machines for the making of recessed filter mouthpieces with a feed screw which is parallel to the path of the filler and separates groups of assorted filter plugs from each other. The operation is slow and the filter plugs are subjected to pronounced mechanical stresses.